There have been a few small hiccups in a couple of areas with KDE so far.
One is the MTP support appears to be not as good as on Thunar (XFCE). I have not been able to get a reliable connection to my Samsung Galaxy J2 phone. As a result I have put a cable onto the Windows 10 computer to enable me to use that to transfer files off the Galaxy J2.
On the other hand the KDE Connect setup seems to work very well and be a viable alternative to Bluetooth for transferring individual files, but it only seems to be able to handle one file at a time.
KDialog is another thing that could work better. Chrome needs this dialog in order to open files, but it is too much like Thunar in not being able to deal with network shares that are offline. I am looking at using another file manager other than Dophin as there are a few alternatives like PCManFM-Qt and possibly Nautilus or Nemo that don't freeze because they can't connect to a network share. Firefox Aurora browser doesn't need to use KDialog so I may end up switching browsers for day to day stuff.
Generally the experience is OK except that resuming from hibernation can be more likely to freeze up.
